An on-vehicle communication device has a communication unit which communicates with a roadside device, a roadside device position information storage unit which stores in advance first position information indicating a position of the roadside device, a vehicle position information acquisition unit which acquires second position information indicating a position of the vehicle, an approach decision unit which decides whether the vehicle approaches the roadside device on the basis of the first position information stored in the roadside device position information storage unit and the second position information that the vehicle position information acquisition unit acquires and a communication control unit which switches a state of the communication unit from a power-saving state to a non-power-saving state in a case where the approach decision unit decides that the vehicle approaches the roadside device.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A communication device which is loaded on a vehicle, the communication device comprising: a transmission and reception circuit that communicates with a roadside device, the transmission and reception circuit configured to switch between a power-saving state and a non-power-saving state; a first memory storing a position of the roadside device in advance; a processor; and a second memory storing a program, when executed by the processor, causes the processor to perform operations comprising: acquiring a position of the vehicle; determining a threshold distance based on 1) a distance that a radio wave emitted from the roadside device travels and 2) a duration for switching a state of the transmission and reception circuit from the power-saving state to the non-power-saving state; determining whether the vehicle approaches the roadside device based on determining that a distance between the position of the roadside device and the position of the vehicle is within the threshold distance; and switching, in response to determining that the vehicle approaches the roadside device, the state of the transmission and reception circuit from the power-saving state to the non-power-saving state to communicate with the roadside device.
2. The communication device according to claim 1 , wherein the state of the transmission and reception circuit switches from the non-power-saving state to the power-saving state when a period of time in which the communication with the roadside device does not start after switching the state of the transmission and reception circuit from the power-saving state to the non-power-saving state reaches a time threshold.
3. The communication device according to claim 2 , wherein the operations further comprises: setting the time threshold in accordance with speed information of the vehicle.
4. The communication device according to claim 1 , wherein the operations further comprises acquiring a scheduled traveling route of the vehicle, and wherein the roadside device is present in a vicinity of the scheduled traveling route of the vehicle.
5. The communication device according to claim 1 , wherein the operations further comprises: acquiring updated information of the position of the roadside device; and updating the position of the roadside device stored in the roadside device position information storage unit.
6. The communication device according to claim 1 , wherein the transmission and reception circuit comprises: a first transmission/reception circuit that transmits and receives a radio signal in a first frequency band which is determined in advance; and a second transmission/reception circuit that transmits and receives the radio signal in a second frequency band which is determined in advance, wherein the communication device further comprises: a first modulation/demodulation circuit which performs modulation and demodulation in accordance with a first modulation system; a second modulation/demodulation circuit which performs modulation and demodulation in accordance with a second modulation system; and a switch circuit that switches a coupling state of the first transmission/reception circuit, the second transmission/reception circuit, the first modulation/demodulation circuit, and the second modulation/demodulation circuit between a first coupling state and a second coupling state, wherein the first coupling state is a state where 1) the first transmission/reception circuit and the first modulation/demodulation circuit are coupled with each other and 2) the second transmission/reception circuit and the second modulation/demodulation circuit are coupled with each other, and wherein the second coupling state is a state where the first transmission/reception circuit and the second modulation/demodulation circuit are coupled with each other.
7. The communication device according to claim 6 , wherein the first frequency band includes 5.8 GHz and 5.9 GHz, and wherein the second frequency band includes 760 MHz.
8. The communication device according to claim 1 , wherein the threshold distance is determined further based on speed information of the vehicle.
9. A communication control method comprising: storing a position of a roadside device into a roadside device position information storage in advance, the roadside device position information storage being installed in a vehicle; acquiring a position of the vehicle; determining a threshold distance based on 1) a distance that a radio wave emitted from the roadside device travels and 2) a duration for switching a state of the transmission and reception circuit from the power-saving state to the non-power-saving state; determining whether the vehicle approaches the roadside device based on determining that a distance between the position of the roadside device and the position of the vehicle is within the threshold distance; and switching, in response to determining that the vehicle approaches the roadside device, a state of the transmission and reception circuit from the power-saving state to the non-power-saving state to communicate with the roadside device.
10. The communication control method according to claim 9 , wherein the state of the transmission and reception circuit switches from the non-power-saving state to the power-saving state when a period of time in which the communication with the roadside device does not start after switching the state of the transmission and reception circuit from the power-saving state to the non-power-saving state reaches a time threshold.
11. The communication control method according to claim 10 , further comprising: setting the time threshold in accordance with speed information of the vehicle.
12. The communication control method according to claim 9 , wherein the threshold distance is determined further based on speed information of the vehicle.
13. A vehicle comprising: a communication device mounted on the vehicle, wherein the communication device comprises: a transmission and reception circuit that communicates with a roadside device, the transmission and reception circuit configured to switch between a power-saving state and a non-power-saving state; a first memory storing a position of the roadside device in advance; a processor; and a second memory storing a program, when executed by the processor, causes the processor to perform operations of: acquiring a position of the vehicle; determining a threshold distance based on 1) a distance that a radio wave emitted from the roadside device travels and 2) a duration for switching a state of the transmission and reception circuit from the power-saving state to the non-power-saving state; determining whether the vehicle approaches the roadside device based on determining that a distance between the position of the roadside device and the position of the vehicle is within the threshold distance; and switching, in response to determining that the vehicle approaches the roadside device, the state of the transmission and reception circuit from the power-saving state to the non-power-saving state to communicate with the roadside device.
14. The vehicle according to claim 13 , wherein the state of the transmission and reception circuit switches from the non-power-saving state to the power-saving state when a period of time in which the communication with the roadside device does not start after switching the state of the transmission and reception circuit from the power-saving state to the non-power-saving state reaches a time threshold.
15. The vehicle according to claim 14 , wherein the operations further comprises: setting the time threshold in accordance with speed information of the vehicle.
16. The vehicle according to claim 13 , wherein the threshold distance is determined further based on speed information of the vehicle.
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August 21, 2018
January 21, 2020
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